When Clint Hurdle sent Josh Harrison to pinch-hit in the ninth inning he was hoping for speed.

Instead he got power.

Harrison hit a walk-off home run to lift the Pirates to a 4-3 victory Tuesday night against the Miami Marlins at PNC Park. It was just the second home run this season for Harrison who has spent most of the year in Class AAA Indianapolis.

"I wasn't necessarily going up there saying 'Let me hit a walk-off home run' " Harrison said. "I was just trying to get on. I knew I'd be the game-winning run."

Turns out he scored and drove in the winning run with one swing.

Facing a 1-1 count against Miami reliever Mike Dunn Harrison laced a line drive toward the right-center field gap. He knew as soon as he made contact that Marlins right field Giancarlo Stanton wouldn't catch the ball. It wasn't until Stanton stopped and watched the ball sail into the bleachers that Harrison realized just how well he struck it.

"He hit that ball and I saw it land in the bleachers and I said 'Wait a minute' " Hurdle said.

With a left-handed pitcher on the mound Hurdle pulled Garrett Jones and inserted Harrison to lead off the ninth. He chose Harrison over Gaby Sanchez who platoons with Jones at first and has much more power than Harrison because he wanted speed.

"I didn't have a homer" Hurdle said.

It was a game that could have -- and probably should have -- slipped away from the Pirates (68-44) at several times as the Marlins (43-68) had baserunners in seven innings multiple baserunners in four. But timely outs and gutsy pitching helped the Pirates stay close as the Marlins stranded 11 and went 3 for 14 with runners in scoring position.

The Pirates wasted an optimal opportunity of their own by squandering a bases-loaded no-outs chance in the eighth. Pedro Alvarez struck out and Russell Martin grounded into an inning-ending double play before the Pirates could plate a run.

Andrew McCutchen bolstered his growing MVP candidacy with a stellar night at the plate and in the field. He made a diving -- and run-saving -- catch in the seventh that preserved a tie score. With runners on first and second Adeiny Hechavarria hit a liner that was hooking toward left field before McCutchen sprinted it down and snared it out of the air.

"I felt like I could get myself in the best position I can get myself into to catch it" McCutchen said. "I feel like I made it look fairly easy because it didn't hurt."